On Apostates

For sometime now I've been wondering what the thinking is behind the contention of cult/nrm scholars/apologists that all accounts by apostates are mere publicity seeking lies, exaggerations, self-justifications,etc. I came across these two articles
http://www.religiousfreedomwatch.org/experts/index.html
which were written for the Scientologists. Though they don't provide citations they do refer to other articles on this issue. Both seem to have been written as arguments against using apostates as expert witnesses in trials.

These articles have helped me understand a bit better what the arguments against apostate accounts consist of. However, it still remains a puzzle to me why these supposed scholars think that "[t]he apostate must always be regarded as an individual who is predisposed to render a biased account of the religious beliefs and practices of his or her former religious associations and activities," whereas current members are not predisposed to render a biased account of their beliefs or organization. Are they really that ignorant that they believe that current members of a controversial religious group would be more objective and truthful about the true nature of the group than former members would be? I'm going to have to read more of those studies because it just doesn't make any sense to me, but perhaps that's because I'm an apostate who knows that the "self-portrait" of TF that Chancellor produced by interviewing only current members is a biased account that is untruthful in many important aspects.